This invention relates to the field of antennas and particularly to flexible, rugged, gain antennas for use on hand-held portable radios.
Several types of antennas are presently used on hand-held radios, the most common being quarter wave whips and physically shorter quarter wave helical antennas. Quarter wave antennas tend to have ground firing lobes with nulls just above the horizon. There is also a strong tendency to have a deep null behind the head of the person holding the radio. Both characteristics are undesirable in hand-held radios as for public safety work. The second major consideration in such design is ruggedness, since portable radios in public safety work are exposed to extremely rough handling, including being dropped on the antenna or being held and swung about by the antenna. Thus, such antennas must be capable of withstanding repeated flexing (to 90.degree.), with no mechanical or electrical damage ensuing. Some designs have been developed utilizing certain flexible elements such as braded wire in coaxial construction, but these typically have soldered wire connections at the feed point and spacers to separate the skirt from the nearest conductive layer, all of which are potentially weak points during repeated flexing. Since such radios must often function in high-noise or other less-than-optimum conditions, a gain antenna is a desired goal which is difficult to combine with ruggedness. The rugged quality should also include a connector with an extremely long-life characteristic. The usual metal-to-metal connector is prone to failure over a long period of use, and even sooner when the radio is swung by the end of the antenna or when the antenna is repeatedly coupled and decoupled.